Date   : Sun, 15 Feb 2004 21:35:10 +0100 (GMT)
From   : Johan Heuseveldt <johan@...>
Subject: Re: Unknown chip

Hi Chris,

On Sun 15 Feb, Chris Johns wrote:
> 
> > If it is actually 28-pin, and given that you found it in a box of roms,
> > I'd plug it into a ROM socket, switch on, and do a *HELP to see if it
> > responds. 

I'm quite positive it's a 24 pins thing. So I can't plug it in...

> > If not, try jumping into it with *FX142,n where n is the ROM
> > socket number to see what is printed on screen.

well, actually it IS possible; changing link S32/S33 (two ROM sockets per
link) this puts the +5v on pin 26 of the socket, which is pin 24 of the ROM.
Maybe I give it a go then, after writing a proglet to read the ROM out and
dump it on a disc.

> A master, or beeb with 1770 DFS wil have *ROMS - I believe this will
> show the ROM even if it doesn't respond to a *HELP. Some ROMs go into
> hibernation if they can't find their hardware (NFS being one of them).

Because it's 24 pins I don't expect it to be in SWR format, and therefor
will not be recognised at all.

The smallest ROM size in 28 pins is 8K, so I think the maximum for this
24-legged thing is 4K. The only 4K's for a Beeb was an old MOS version,
consisting of four 4K ROMs. Perhaps this one of them???

  ( S32/S33 are just two of the many links to recreate the four sockets
      of IC 52,88,100,101 for the MOS, and socket IC 51 for a single
      language ROM )

I'll let you know.


greetings,
Johan

-- 
Johan Heuseveldt <johan@...              >
  aka  waarland

  The best place is a Riscy place
 
Why did Shakespeare use so many famous quotations in his work?